The present invention relates generally to a wiper motor control system for clearing windows including, but not limited to, an automotive windshield or rear window wiper blade or blades, which automatically operates and controls the operating speed of a wiper blade or blades according to rain or moisture conditions. More particularly, the invention relates to a wiper motor control system having an exterior sensor which continually monitors moisture conditions on the windshield or rear window and is influenced thereby to remain inoperative or to operate the wiper motor in one of two speeds according to this influence. The sensor is positioned within an area swept by the wiper blades.
U.S. Pat. No. 4,554,493 teaches an apparatus for automatic activation and control of windshield wiper blades in response to moisture accumulation at the exterior surface of the windshield, including a pair of wires sandwiched within the windshield laminate and positioned below the surface of the windshield. The wiper blades provide a variable capacitance to a detection circuit. Wiper blade action is initiated when the capacitance measurement exceeds a predetermined reference standard.
U.S. Pat. No. 4,463,294 teaches a control circuit for a windshield wiper motor which utilizes a plurality of infrared emitters that emit a chain of infrared pulses towards a plurality of infrared sensors. When rain passes between the infrared emitters and sensors, the rain interrupts the flow of pulses therebetween. A control circuit senses the missed pulses and selectively energizes a low-speed, mid-speed, and high-speed windings associated with the wiper motor.
U.S. Pat. No. 4,495,452 teaches a windshield wiper motor control which receives information as to the amount of moisture on the windshield through a sensor within the area swept by the windshield wipers. The sensor may be of the capacitive type and may generate an AC-signal the frequency of which is indicative of the relative humidity of the windshield. The sensor and circuit of this teaching is susceptible to temperature changes and impurities present on a dry windshield.
U.S. Pat. No. 4,527,105 teaches additional means for automatic operation of windshield wiper motors.
All improved automatic window wiper motor system which overcome the short comings of the prior art and improves safety, especially, when used in the control of automobile windshield and rear window wipers would find wide acceptance.